Reviving or increasing the production of clogged or congested oil wells



March 2, 1954 C. s. ACKLEY 2,670,802 REvIvINO OR INCREASING THE PRODUCTION OE OLOGGEO OR OONGEsIED OIL wELLs 2 Sheets-Sheet l Filed Dec. 16. 1949 A INVENTOR. fsa/mss' 5674/126? March 2, 1954 .cg s ACKLEY 2,670,802

- REVIVING OR REASING THE PRODUCTION OF CLOGGED CONGESTED OIL WELLS Filed Deo. 16. 1949 2 Sheets-Sheet 2 I INVENTOR. 5s/Avis .5'. 4617.452

Patented Mar. 2, 1954 UNITED STATES PATENr OFFICE Charles S. Ackley, Brooklyn, N. Y., .assigner to Thermactor Company, ANew York, N. Y., a corporation of Delaware Applicationnecember 16, 1949, seriaLNwisaasi The invention .herein disclosed relates to the reactivation of oil wells which have lost .production or become dormant rthrough vthe clogging action within the koil sand of congealing wax, gum or sludge present in the oil.

The refrigerationeffected by expansion of the volatile constituents of a ilowing well always yhas an adverse effect tending to make a well seal itself on, and it -is common knowledge that the oil left in a .well at theend of `what may vbeconsidered economical production, is usually much more than that taken out.

The present invention vhas been developed particularly with a view to .restoring such nonproductive though actually valuable, dormant Wells to economical and .proiitable production.

Particularly itis a purpose of the invention to accomplish such results witha vminimum of .new equipment and expense and with full .utilization of .the well equipment .that may be in place in the sand and in so doing., to .create and maintain a hot oil pool spreading from .the well into the surrounding structure and .serving thereby as a restoring agent and as an increasing and sustaining reservoir of production oil.

'Further special objects in this connection are to provide satisfactory controls `for .maintaining the hot oil pool so created more or less .constant inthe extent to which it can be supported by the adjacent or surrounding structure.

Other desirable objects attained by the `invention are set forth and will appear in the course of the following specication denning and broadly covering the invention.

The drawings accompanying and forming part of the specification illustrate certain Apresent practical embodiments of the invention. .Structure and arrangement, however, may be modified and changed as regards such illustration, all within the true intent and broad scope of the invention as hereinafter dened and claimed.

Fig. l in the drawings is a broken sectional view illustrating diagrammatically installation. and operation of the invention for increasing pro duction in a producing well having a declining rate of production;

Fig. 2 is a similar view showing features of the invention as installed in one of the pressurizing Wells of a secondary recovery system;

Fig. 3 is a broken part sectional and perspective view illustrating diagrammatically a typical :five spot layout embodying the invention.

1 claim. I(cl. 16e-23) l .In thecase of a well which is actually producing., but rat a declining rate, the invention may be applied substantially as shown in Fig. l. y

In this view a cased oil well is indicated, having a ,perforated liner .5 in the oil sand at the Y lower end of the casing `l.

vA well head l ,is shown applied tothe casing,l

designed to pass the flow ytubingr and power cable for the electric heater carried by the tubing. heater, asmore fully disclosed in cepending patent application Serial No. 126,089, led November .8, 1949, nowPatent No. 2,632,836, is .of

novel construction, particularly .in that it is of 1 y clamps .i3 loosely seated on the couplings i0. Q

A thermostat set to maintain a desired mean temperature is indicated at le, mounted `on the upper end of the heater.

`A pump is shown at i5 connected in the .flow tubing above the heater1 adapted to vbe operated in the usual way .by sucker rods i6.

The well head may have `a vstuilingbozior.

erably at a Ylevel above the meltingpoint of .the

waxy and gummy constituents'o the oil and below thegasiication temperature of the lighter components of the oil, the heater may .be left.A

on as long as need be to dissolve the congealed materials and cause the thinned, heated oil to penetrate and impartite heat to the surrounding structureto create more or less ,of a spreading pool of hot oil. As lthis Vheated body `expands and Works back into the structure, more .and more of the blocked or congealed ,oilis .released to now back into the. Well and rise in the ,casing andow tubing.

There is, however, a limit to which the heated oil will work outwardly from the well by natural pressure, because due to friction in the sand a balance point is reached that will arrest further outward movement and spread of the hot oil pool.

The time required for building up a sufficient pool of the hot oil will vary with diiferent structures and the extent to which a producing Well may have been depleted.

At any rate, pumping may be started and maintained continuously or intermittently and at a rate proportionate to the build-up of the pool.

Preferably heating and pumping operations are so coordinated as to surely maintain the heater covered at all times with oil.

Also, it is important to remove the oil at a rate su'icient to prevent the hot oil from rising much above the oil sand to avoid heat transfer through the casing to the cooler, surrounding ground barren of oil.

To maintain the oil level at or as near the top of the oil sand as possible, the speedof operation of the pump may be governed, or in some instances the pump may be operated for several 'hours and then shut down, in effect maintaining successive cycles of pumping and heating. Or heating may be continued and pumping effected intermittently, or pumping continued and heating applied in successive intervals, the invention enabling choice of these conditions to meet different situations.

Generally the overburden affords complete insulation, enabling eiective application of heat to maintain the maximum reservoir of hot oil which the structure will support.

This hot oil is the more readily removed by the pump, so the pump is to that extent rendered the more effective. The flow tubing is completely open straight down through the heater and this also is a factor in increasing the recovery rate.

In dormant wells, which have ceased to produce and been abandoned, the same hot pooling method may be followed and the expenses involved may generally be justied, considering that such kwells may retain usually from 40% to 70% of the primary oil in the reservoir. These wells, in most or many cases, have become dormant because of blocked pores filled with wax, sludge or congealed oil which have gradually sealed the porous sand structure and stopped movement of oil through the well.

At the time of abandonment the casing may have been removed and the wells left to cave or fill in with earth and water. To revive such wells involves cleaning out and re-casing to the oil sand, but this ordinarily may be less costly than drilling new wells. In many cases these abandoned wells are left with the casing in place. Unless wells have been abandoned because of the intrusion of salt water into the oil sand, they may profitably be reconditioned under the present invention, utilizing the structure and plan outlined in Figs. 2 and 3.

This may be a pressurizing operation such as practiced in secondary recovery fields, with a number of pressurizing wells grouped about a more or less centrally located outlet well.

A typical arrangement of this character is indicated in Fig. 3, with four pressure injecting Wells I9 grouped in the pattern of a square or rectangle about a substantially centrally located outlet well 20.

Flow tubing 9 carrying the open tubular heaters as previously described, are installed in the pres- 4 sure wells and the outlet well which is cased and has a perforated liner at the bottom, may be left open and be connected and arranged for delivery of oil to storage or tankage.

To revive and restore flow of oil from such a well may require an appreciable length of time, as the sand structure in such a location must'be thoroughly warmed to in eiect thaw out and liquify the waxes or congealed oil by which the sand is sealed. rThe wells containing the heaters may be primed with oil from the surface from time to time, as required to keep the heaters covered. This oil may be introduced through the flow tubing.

In this installation, with no pump or pumping gear, the flow tubing to which the heater is attached has a continuous, unobstructed passage through it from top to bottom. This enables the tubing to be used for gaging the depth of oil accumulating within it.

Before pressurizing, the wells are sealed off at approximately the upper sand level by packers 2l closing the annular well space between the casing and ow tubing. These packers, as indicated in Fig. 2, may have suitable stufng boxes 22 or the like for sealing the power cables therethrough.

After gaging the depth of oil in the open flow tubing and determining that a sufficient pool of hot oil has been built up around and above the heater, the well head 1 may be attached, ready for pressurizing.

The Well head in this case may carry a pressure line 23 and a relief line 24 connected with the flow tubing and equipped with check valve 26, pressure gage 25, pressure relief valve 21 and possibly other accessories, as required.

Natural gas, if available, or compressed air may be used as the pressure fluid. This pressurizing fiuid introduced through the iiow tubing under pressure high enough to prevent the entry of well oil into the iiow tubing at 8 will, upon Contact with the hot inner tube of the heater, expand and comingle with the heated oil within the well and surrounding oil structure. The expansive force of the hot gas drives the heated oil further and further into the congested structure.

The pool of oil surrounding the heater may be replenished from time to time, to take the place of the oil forced back into the structure, by introducing oil, as required, with the pressurizing gas.

Control of pressure and temperature may be effected under guidance of the recording of surface instruments to attain the best results.

The pressurized oil reaching the outlet Well may be delivered under its own pressure or be pumped to a surface pipe line or to tankage.

In this case also the heating of the oil facilitates delivery operations and prevents deposit of paraiiin or other effects that might impede or slow up the action.

The invention thus differs materially from cold water and other pressurizing operations Which may tend to chill and congeal the petroliferous products instead of thinning and rendering them the more fluid.

The output of the production well may be controlled or kept at such a rate `as will maintain the level of heated oil in the pressurized well above the heater therein and maintain the hot oil pool surrounding the pressurized well.

The new equipment required for practicing the invention is relatively simple and can be used in conjunction with the existing Well equipment. Operations are readily controlled in diierent ways to meet special conditions in different locations. The straight through, open construction of the heaters and their mounting on the ow tubing provide for free flow of uid in eithery i products and comprising providing I'low tubing and tubular heater having a continuous, open flow passage therethrough of the same extent and introducing said flow tubing and tubular heater into one well to a depth with the heater in the oil sand locale, packing 01T that well about the flow tubing substantially at the upper level of the oil sand, energizing the heater to liquify and reduce the viscosity of petroliferous products in said Well and immediately surrounding structure to form a hot oil pool and forcing a pressure uid down through said flow tubing and out through the corresponding fully open ow passage of said tubular heater into the hot pool of oil created by said heater in the packed-off portion of the well and the surrounding structure to thereby enforce migration of the lowered viscosity pool contents to the well adjoining and open to the same oil sand, controlling the heater in temperature and time to maintain temperature of the heated oil in the pressurized well above the melting point of waxes and gums and below the gasifying temperature of volatile constituents of the oil, and controlling output of said adjoining Well at a rate to maintain the level of heated oil in the pressurized well above the heater and to maintain the hot oil pool surrounding the pressurized well.

CHARLES S. ACKLEY.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,354,757 Popcke Oct. 5, 1920 1,433,871 Burks et yal Oct. 31, 1922 1,648,242 Powell Nov. 8, 1927 1,726,041 Powell Aug. 27, 1929 2,134,610 Hogg Oct. 25, 1938 2,444,756 Steffen July 6, 1948 2,472,445 Sprong June 7, 1949 OTHER REFERENCES Reistle, C. E., Jr.: Parain and Congealing- Oil Problems, U. S. Bureau of Mines, Bulletin 348, page 97, U. S. Govt. Printing Oflice, Wash- Y ington, 1932. 

